1. Field of the Invention
The present invention relates to an electromagnetic shielding composite and method for making the same.
2. Discussion of Related Art
With the development of information technology, the harmful effects of electromagnetic interference, electromagnetic leakage, and electromagnetic radiation has attracted a lot of attention. And now, metal materials with good conductivity, such as copper and silver, are widely used as electromagnetic shielding materials. However, the metal materials have some disadvantages, such as high cost, high density, easy to oxidize and erode.
Carbon nanotubes (CNTs) are a novel carbonaceous material and have received a great deal of interest since the early 1990s. CNTs have a large ratio of length/diameter (being always more than 1000). This special structure ensures they have excellent electrical and mechanical properties, such as better conductivity than copper among other things. Due to these properties, CNTs have become an important new material for use in electromagnetic shielding.
Nowadays, the method for using CNTs in electromagnetic shielding is by dispersing the CNTs in polymer to form a composite. But due to their small diameter and large surface energy, the CNTs are easy to agglomerate. A process of surface modification is used to avoid agglomeration. However, this process of surface modification has the following disadvantages among others: firstly, the process results in defects of the walls of the CNTs, such as decreasing the length/diameter ratio, which negatively impacts conductivity and other properties thereof, and thereby affects the property of electromagnetic shielding; secondly, this method is only suitable for combining CNTs with just a few types of polymers, which restricts the scope of applications; and thirdly, the method of surface modification is expensive.
What is needed, therefore, is an electromagnetic shielding composite and method for making the same, with good electromagnetic shielding properties, and the method for making the electromagnetic shielding composite is simple and without need of a surface pre-treatment for the CNTs.